The overall object of the proposed research is to study the functional behavior of hemoglobin, with particular emphasis on the mechanism of ligation reactions. Human variants: Hb Sydney Val Ell (G7) yields Ala; Hb Zurich His B(63) yields Arg; Hb Hammersmith B(42) Phe yields Bryn Mawr Phe B(85) yields Ser; fetal hemoglobins (FI, FII); the minor components of normal adult hemoglobins (AIa,AIb,AIc) and cat hemoglobins have been selected for the present study. BIBLIOGRAPHIC REFERENCES: Sharma, V.S., Schmidt, M.R. and Ranney, H.M.: Dissociation of CO from Carboxyhemoglobin. J. Biol. Chem. 251:4267-4272, 1976. Sharma, V.S. and Ranney, H.M.: Allosteric equilibrium between R and T forms of nitrosylhemoglobin: A kinetic study. Fed. Proc. 36: 890A, 1977.